1. Articles from Erich Götzinger

    1-24 of 56 1 2 3 »
    1. Spectral degree of polarization uniformity for polarization-sensitive OCT

      Spectral degree of polarization uniformity for polarization-sensitive OCT

      Depolarization of light can be measured by polarization-sensitive optical coherence tomography (PS-OCT) and has been used to improve tissue discrimination as well as segmentation of pigmented structures. Most approaches to depolarization assessment for PS-OCT – such as the degree of polarization uniformity (DOPU) – rely on measuring the uniformity of polarization states using spatial evaluation kernels. In this article, we present a different approach which exploits the spectral dimension. We introduce the spectral DOPU for the pixelwise analysis of polarization state variations between sub-bands of the broadband light source spectrum. Alongside a comparison with conventional spatial and temporal DOPU algorithms, we demonstrate ...

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    2. Polarisation-sensitive OCT is useful for evaluating retinal pigment epithelial lesions in patients with neovascular AMD

      Polarisation-sensitive OCT is useful for evaluating retinal pigment epithelial lesions in patients with neovascular AMD

      Background/aims To examine the reproducibility of lesion dimensions of the retinal pigment epithelium (RPE) in neovascular age-related macular degeneration (AMD) with polarisation-sensitive optical coherence tomography (PS-OCT), specifically imaging the RPE. Methods Twenty-six patients (28 eyes) with neovascular AMD were included in this study, and examined by a PS-OCT prototype. Each patient was scanned five times at a 1-day visit. The PS-OCT B-scan located closest to the macular centre presenting with RPE atrophy was identified, and the longitudinal diameter of the lesion was quantified manually using AutoCAD 2008. This procedure was followed for the identical B-scan position in all five ...

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    3. Peripapillary rat sclera investigated in vivo with polarization sensitive optical coherence tomography

      Peripapillary rat sclera investigated in vivo with polarization sensitive optical coherence tomography

      Purpose: To demonstrate polarization sensitive (PS) optical coherence tomography (OCT) for non-invasive, volumetric, and quantitative imaging of the birefringent properties of the peripapillary rat sclera. To compare the findings in PS-OCT images to state-of-the-art histomorphometric analysis of the same tissues. Methods: A high-speed PS-OCT prototype operating at 840 nm was modified for imaging the rat eye. Densely sampled PS-OCT raster scans covering an area of ~1.5 mm × 1.5 mm centered at the papilla were acquired in the eyes of anesthetized, male Sprague Dawley rats. Cross-sectional PS-OCT images were computed and fundus maps displaying the birefringent properties of the ...

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    4. Imaging Retinal Pigment Epithelial Proliferation Secondary to PASCAL Photocoagulation In Vivo by Polarization-sensitive Optical Coherence Tomography

      Imaging Retinal Pigment Epithelial Proliferation Secondary to PASCAL Photocoagulation In Vivo by Polarization-sensitive Optical Coherence Tomography

      Purpose To image the retinal pigment epithelium (RPE) after macular laser and to monitor healing responses over time in vivo in patients with diabetic maculopathy using polarization-sensitive optical coherence tomography (OCT). Design Prospective, nonrandomized clinical trial. Methods In this single-center trial (Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria), 13 patients (13 eyes) underwent grid photocoagulation for diabetic maculopathy. Retinal healing processes were continuously followed over the course of 3 months. A polarization-sensitive OCT prototype was used, allowing detection and measurement of the RPE changes based on their specific polarization-scrambling qualities. Results After 1 day, the intraretinal ...

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    5. Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser

      Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser

      We present a novel, high-speed, polarization-sensitive, optical coherence tomography set-up for retinal imaging operating at a central wavelength of 1060 nm which was tested for in vivo imaging in healthy human volunteers. We use the system in combination with a Fourier domain mode locked laser with active spectral shaping which enables the use of forward and backward sweep in order to double the imaging speed without a buffering stage. With this approach and with a custom designed data acquisition system, we show polarization-sensitive imaging with an A-scan rate of 350 kHz. The acquired three-dimensional data sets of healthy human volunteers ...

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    6. Measuring Retinal Nerve Fiber Layer Birefringence, Retardation, and Thickness Using Wide-Field, High-Speed Polarization Sensitive Spectral Domain OCT

      Measuring Retinal Nerve Fiber Layer Birefringence, Retardation, and Thickness Using Wide-Field, High-Speed Polarization Sensitive Spectral Domain OCT

      Purpose. We presented a novel polarization sensitive optical coherence tomography (PS-OCT) system for measuring retinal nerve fiber layer (RNFL) birefringence, retardation, and thickness, and report on the repeatability of acquiring these quantities. Methods. A new PS-OCT system, measuring at 840 nm, was developed that supports scan angles of up to 40° × 40° with an A-scan rate of 70 kHz. To test the performance and reproducibility, we measured 10 eyes of 5 healthy human volunteers five times each. All volunteers were imaged further with scanning laser polarimetry (SLP). The obtained RNFL birefringence, retardation, and thickness maps were averaged, and standard deviation ...

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    7. Lesion Size Detection in Geographic Atrophy by Polarization-sensitive Optical Coherence Tomography and Correlation to Conventional Imaging Techniques

      Lesion Size Detection in Geographic Atrophy by Polarization-sensitive Optical Coherence Tomography and Correlation to Conventional Imaging Techniques

      Purpose: To investigate the reproducibility of automated lesion size detection in patients with geographic atrophy (GA) using polarization-sensitive spectral domain-OCT (PS-OCT) and to compare findings with scanning laser ophthalmoscopy (SLO), fundus autofluorescence (FAF), and intensity based SD-OCT. Methods: 29 eyes of 22 patients with GA were examined by PS-OCT, selectively identifying the retinal pigment epithelium (RPE). A novel segmentation algorithm was applied, automatically detecting and quantifying areas of RPE atrophy. The reproducibility of the algorithm was assessed and lesion sizes were correlated with manually delineated SLO, FAF and intensity based SD-OCT images to validate the clinical applicability of PS-OCT in ...

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    8. High-speed polarization sensitive optical coherence tomography scan engine based on Fourier domain mode locked laser

      High-speed polarization sensitive optical coherence tomography scan engine based on Fourier domain mode locked laser

      We report on a new swept source polarization sensitive optical coherence tomography scan engine that is based on polarization maintaining (PM) fiber technology. The light source is a Fourier domain mode locked laser with a PM cavity that operates in the 1300 nm wavelength regime. It is equipped with a PM buffer stage that doubles the fundamental sweep frequency of 54.5 kHz. The fiberization allows coupling of the scan engine to different delivery probes. In a first demonstration, we use the system for imaging human skin at an A-scan rate of 109 kHz. The system illuminates the sample with ...

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    9. Large-field high-speed polarization sensitive spectral domain OCT and its applications in ophthalmology

      Large-field high-speed polarization sensitive spectral domain OCT and its applications in ophthalmology
      We present a novel spectral domain polarization sensitive OCT system (PS-OCT) that operates at an A-scan rate of 70 kHz and supports scan angles of up to 40° × 40°. The high-speed imaging allows the acquisition of up to 1024 × 250 A-scans per 3D scan, which, together with the large field of view, considerably increases the informative value of the images. To demonstrate the excellent performance of the new PS-OCT system, we imaged several healthy volunteers and patients with various diseases such as glaucoma, AMD, Stargardt’s disease, and albinism. The results are compared with clinically established methods such as scanning ...
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    10. Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization

      Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization

      Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT. In addition to imaging based on tissue reflectivity, PS-OCT also enables depth-resolved mapping of sample polarization properties such as phase-retardation, birefringent axis orientation, Stokes vectors, and degree of polarization uniformity (DOPU). In this study, PS-OCT was used to investigate the polarization properties of melanin. In-vitro measurements in samples with varying melanin concentrations revealed polarization scrambling, i.e. depolarization of backscattered light. Polarization scrambling in the PS-OCT images was more pronounced for higher melanin concentrations and correlated with the concentration of the melanin granules in the phantoms. Moreover, in-vivo ...

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    11. High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source

      High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source

      Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human posterior eye segment (retina, choroid, sclera), as it permits a long penetration depth. Complementary to structural images, polarization-sensitive OCT (PS-OCT) images visualize birefringent, polarization-maintaining or depolarizing areas within the sample. This information can be used to distinguish retinal layers and structures with different polarization properties. High imaging speed is crucial for imaging ocular structures in vivo in order to minimize motion artifacts while acquiring sufficiently large datasets. Here, we demonstrate PS-OCT imaging at 350 kHz A-scan rate using a two-channel PS-OCT system in ...

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    12. Feature Of The Week 4/29/12: Medical University of Vienna Demonstrates Automated Measurement of Choroidal Thickness in the Human Eye by PS-OCT

      Feature Of The Week 4/29/12: Medical University of Vienna Demonstrates Automated Measurement of Choroidal Thickness in the Human Eye by PS-OCT

      Researchers at the Medical University of Vienna have a long history of outstanding contributions to the field of Optical Coherence Tomography dating back 25 years.  This week work by Dr. Hitzenberger, one of the pioneers of the field, and his colleagues is featured demonstrating automated measurement of choroidal thickness in the human eye by polarization sensitive optical coherence tomography. Below is a summary of their work.Imaging of retinal layers and quantitative measurements of their thickness are among the most important applications of OCT. E.g., the total retinal thickness is an important quantity for diagnosis of diabetic retinopathy, the ...

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    13. High-Speed Retinal Imaging with Polarization-Sensitive OCT at 1040 nm

      High-Speed Retinal Imaging with Polarization-Sensitive OCT at 1040 nm

      Purpose. To demonstrate the ability of a new high-speed polarization-sensitive optical coherence tomography (PS-OCT) system for retinal imaging at 1040 nm. Methods. A new polarization-sensitive swept source OCT system in the 1 [mu]m wavelength range is used to image the retina of healthy volunteers. The instrument is operated at an A-scan rate of 100 kHz which is about three times faster than previously reported PS-OCT instruments in this wavelength region. The increased imaging speed can be used to record densely sampled volumes of the retina. Moreover, it enables averaging of several B-scans recorded at the same location to obtain ...

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    14. Automated measurement of choroidal thickness in the human eye by polarization sensitive optical coherence tomography

      Automated measurement of choroidal thickness in the human eye by polarization sensitive optical coherence tomography

      We present a new method to automatically segment the thickness of the choroid in the human eye by polarization sensitive optical coherence tomography (PS-OCT). A swept source PS-OCT instrument operating at a center wavelength of 1040 nm is used. The segmentation method is based entirely on intrinsic, tissue specific polarization contrast mechanisms. In a first step, the anterior boundary of the choroid, the retinal pigment epithelium, is segmented based on depolarization. In a second step, the choroid-sclera interface is found by using the birefringence of the sclera. The method is demonstrated in five healthy eyes. The mean repeatability (standard deviation ...

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    15. Morphologic Characteristics of Idiopathic Juxtafoveal Telangiectasia Using Spectral-Domain and Polarization-Sensitive Optical Coherence Tomography

      Morphologic Characteristics of Idiopathic Juxtafoveal Telangiectasia Using Spectral-Domain and Polarization-Sensitive Optical Coherence Tomography
      Purpose: Idiopathic juxtafoveal telangiectasia (IJT) is characteristically associated with pigmentary changes. Polarization-sensitive spectral-domain optical coherence tomography (PS-SD-OCT) enables imaging of the retinal pigment epithelium (RPE) and similar melanin-containing structures based on specific polarization properties. This study examined IJT with the latest-generation SD-OCT and PS-SD-OCT, identifying pathophysiologically relevant characteristics of the retinal layers and RPE. Methods: Twenty-two eyes of 12 patients with IJT were examined by PS-SD-OCT, with special focus on RPE detection and segmentation. Furthermore, SD-OCT technology (Cirrus, Spectralis, and 3D-OCT-1000) was applied. Characteristics of the retinal layers and RPE were evaluated. A classification system based on OCT characteristics of ...
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    16. Speckle noise reduction in high speed polarization sensitive spectral domain optical coherence tomography

      Speckle noise reduction in high speed polarization sensitive spectral domain optical coherence tomography
      We present a high speed polarization sensitive spectral domain optical coherence tomography system based on polarization maintaining fibers and two high speed CMOS line scan cameras capable of retinal imaging with up to 128 k A-lines/s. This high imaging speed strongly reduces motion artifacts and therefore averaging of several B-scans is possible, which strongly reduces speckle noise and improves image quality. We present several methods for averaging retardation and optic axis orientation, the best one providing a 5 fold noise reduction. Furthermore, a novel scheme of calculating images of degree of polarization uniformity is presented. We quantitatively compare the ...
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    17. Speckle noise reduction by averaging in polarization sensitive spectral domain optical coherence tomography

      Speckle noise reduction by averaging in polarization sensitive spectral domain optical coherence tomography
      We demonstrate an ultra high speed fiber based polarization sensitive spectral domain optical coherence tomography system, using two ultra high speed CMOS line scan cameras. With this system an A-scan rate of up to 128 kHz was achieved. The system is based on polarization maintaining fibers and retrieves the backscattered intensity, retardation and optic axis orientation with only one A-scan per measurement location. This high speed data acquisition enables averaging of several acquired B-scans of intensity, retardation, optic axis orientation, and Stokes vectors, which strongly reduces speckle noise. We discuss different averaging techniques and compare the results in healthy human ...
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    18. In vivo observation of human retinal-cone outer-segment renewal

      In vivo observation of human retinal-cone outer-segment renewal
      Cone-disk shedding and generation can be observed using transverse-scanning optical coherence tomography and scanning-laser ophthalmoscopy. Vision is one of the most complex human senses. The eye projects images from our environment onto the retina, which consists of a variety of different cells. The retina preprocesses this information before sending it to the brain as electrical signals. Many different retinal diseases—such as age-related macular degeneration—distort the fragile retinal structure, leading to (for example) reduced visual perception and eventual blindness. Maintenance of a healthy retina requires interactions between its photosensitive cells and the retinal-pigment epithelium (RPE). There are two different ...
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    19. Ultra-high-speed polarization sensitive OCT in the human retina using a single spectrometer

      Ultra-high-speed polarization sensitive OCT in the human retina using a single spectrometer

      We present a single spectrometer functional spectral domain optical coherence tomography system, which allows for encoding additional information within the spatial frequencies. The method is based on a differentiation between orthogonal polarization channels through spatial modulation introduced by an electro-optic modulator. This method is used to perform Ultrahigh- speed retinal polarization sensitive optical coherence tomography (PSOCT). With this setup, we realized for the first time polarization sensitive OCT measurements of the human retina in-vivo, with camera line rates of up to 160.000 A-scans per second. Compared to PSOCT systems, operating at traditional line rates, this significantly improves patient comfort ...

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    20. Spectral domain polarization sensitive optical coherence tomography at 1.55 μm: novel developments and applications for dynamic studies in materials science

      Spectral domain polarization sensitive optical coherence tomography at 1.55 μm: novel developments and applications for dynamic studies in materials science
      In this paper it is demonstrated, how research in optical coherence tomography (OCT) for biomedical diagnostics successfully triggered new developments in the field of mechanical material testing. With the help of a specifically designed, compact and robust spectral domain polarization sensitive OCT (SD-PS-OCT) setup, which is operating at 1.55 μm, dynamic investigations of technical materials - like bulk polymers and composite samples - can be performed under various conditions. Already by evaluating the speckle pattern of the standard SD-OCT images with advanced image processing methods, valuable information on the deformation and flow characteristics of samples subjected to tensile tests can be ...
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    21. Visualization of microvasculature by dual-beam phase-resolved Doppler optical coherence tomography

      Visualization of microvasculature by dual-beam phase-resolved Doppler optical coherence tomography

      We present a dual-beam Doppler optical coherence tomography system for visualizing the microvasculature within the retina. The sample arm beams from two identical spectral domain optical coherence tomography (SD-OCT) systems are combined such that there is a small horizontal offset between them at the retina. Thereby we record two tomograms which are slightly separated in time. Phase-resolved Doppler analysis is performed between these two data sets. This system allows blood capillary imaging with high flow sensitivity and variable velocity range. To demonstrate the performance of our system we present images of the microvascular network around the fovea and around the ...

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    22. Dynamic optical studies in materials testing with spectral-domain polarization-sensitive optical coherence tomography

      Dynamic optical studies in materials testing with spectral-domain polarization-sensitive optical coherence tomography
      By combining dynamic mechanical testing with spectral-domain polarization-sensitive optical coherence tomography (SD-PS-OCT) performed at 1550 nm we are able to directly investigate for the first time changes within scattering technical materials during tensile and fracture tests. Spatially and temporally varying polarization patterns, due to defects and material inhomogeneities, were observed within bulk polymer samples and used to finally obtain – with the help of advanced image processing algorithms – quantitative maps of the evolving internal stress distribution. Furthermore, locally increased stress within fiber-reinforced composite materials was identified in situ with SD-PS-OCT to cause depolarizing sites of fiber-matrix debonding prior the onset of ...
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    23. Sample motion-insensitive, full-range, complex, spectral-domain optical-coherence tomography

      Sample motion-insensitive, full-range, complex, spectral-domain optical-coherence tomography

      We present a full-range, complex, spectral-domain optical-coherence-tomography (SD-OCT) system that is based on a double-beam scanning approach. The sample beams of two identical SD-OCT setups are combined collinearly by a bulk optic beam splitter before illuminating the object. The required phase shift for the complex signal reconstruction comes from the phase difference between both interferometers. Because of the double-beam scanning approach, our system is completely insensitive to sample motion. To demonstrate the performance of our setup, we present images of the human optic nerve head in vivo and of a human tooth.

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    24. Segmentation and quantification of retinal lesions in age-related macular degeneration using polarization-sensitive optical coherence tomography

      Segmentation and quantification of retinal lesions in age-related macular degeneration using polarization-sensitive optical coherence tomography
      We present polarization-sensitive optical coherence tomography (PS-OCT) for quantitative assessment of retinal pathologies in age-related macular degeneration (AMD). On the basis of the polarization scrambling characteristics of the retinal pigment epithelium, novel segmentation algorithms were developed that allow one to segment pathologic features such as drusen and atrophic zones in dry AMD as well as to determine their dimensions. Results from measurements in the eyes of AMD patients prove the ability of PS-OCT for quantitative imaging based on the retinal features polarizing properties. Repeatability measurements were performed in retinas diagnosed with drusen and geographic atrophy in order to evaluate the ...
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    1-24 of 56 1 2 3 »
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    1. (56 articles) Medical University of Vienna
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